s=input()
s1=''
for a in  s:
    if (a=='(' or a=='{' or a=='[' or a=='<' ) or s1=='':
           s1+=a
    elif s1!='':
        if (a==')' and s1[-1]=='(' )or (a=='}' and s1[-1]=='{')  or (a==']' and s1[-1]=='[' ) or(a=='>' and s1[-1]=='<' ):
            s1=s1[:-1]
if s1=='':
    print('верная')
else:
    print('неверная')